Central locking system problems

[du6mig6]

Hello to all and excuse me for my bad english!

I wonder if anyone can help me!?

I own X5, 2004, 3.0 D, european version.

The situation is as follows :
Once car is strated and I drive, on reaching some speed - all doors lock, that is normal I suppose, however that was not happening once I bought it!

The problem is that doors automatically do not open once ignition is off, so if anyone sitting in car pulls the handle to open the door it stucks and you have to triger central lock from inside to open-close and open once again to restore once again.

Would appreciate if anyone can suggest me how to deal with my problem!?

Thanks in advance.:p